package com.huadao.pda.data.http;

import java.io.IOException;
import java.io.InputStream;
import java.security.KeyManagementException;
import java.security.KeyStore;
import java.security.NoSuchAlgorithmException;
import java.security.cert.Certificate;
import java.security.cert.CertificateException;
import java.security.cert.CertificateFactory;
import java.security.cert.X509Certificate;

import javax.net.ssl.HostnameVerifier;
import javax.net.ssl.KeyManager;
import javax.net.ssl.KeyManagerFactory;
import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLSession;
import javax.net.ssl.SSLSocketFactory;
import javax.net.ssl.TrustManager;
import javax.net.ssl.TrustManagerFactory;
import javax.net.ssl.X509TrustManager;

public class HttpsUtils {

    public static class SSLParams {

        public SSLSocketFactory sSLSocketFactory;

        public X509TrustManager trustManager;

    }

    public static SSLParams getSslSocketFactory() {

        return getSslSocketFactoryBase(null, null, null);

    }

    /**
     * https单向认证
     * <p>
     * 可以额外配置信任服务端的证书策略，否则默认是按CA证书去验证的，若不是CA可信任的证书，则无法通过验证
     */

    public static SSLParams getSslSocketFactory(X509TrustManager trustManager) {

        return getSslSocketFactoryBase(trustManager, null, null);

    }

    /**
     * https单向认证
     * <p>
     * 用含有服务端公钥的证书校验服务端证书
     */

    public static SSLParams getSslSocketFactory(InputStream... certificates) {

        return getSslSocketFactoryBase(null, null, null, certificates);

    }

    /**
     * https双向认证
     * <p>
     * bksFile 和 password -> 客户端使用bks证书校验服务端证书
     * <p>
     * certificates -> 用含有服务端公钥的证书校验服务端证书
     */

    public static SSLParams getSslSocketFactory(InputStream bksFile, String password, InputStream... certificates) {

        return getSslSocketFactoryBase(null, bksFile, password, certificates);

    }

    /**
     * https双向认证
     * <p>
     * bksFile 和 password -> 客户端使用bks证书校验服务端证书
     * <p>
     * X509TrustManager -> 如果需要自己校验，那么可以自己实现相关校验，如果不需要自己校验，那么传null即可
     */

    public static SSLParams getSslSocketFactory(InputStream bksFile, String password, X509TrustManager trustManager) {

        return getSslSocketFactoryBase(trustManager, bksFile, password);

    }

    private static SSLParams getSslSocketFactoryBase(X509TrustManager trustManager, InputStream bksFile, String password, InputStream... certificates) {

        SSLParams sslParams = new SSLParams();

        try {

            KeyManager[] keyManagers = prepareKeyManager(bksFile, password);

            TrustManager[] trustManagers = prepareTrustManager(certificates);

            X509TrustManager manager;

            if (trustManager != null) {

//优先使用用户自定义的TrustManager

                manager = trustManager;

            } else if (trustManagers != null) {

//然后使用默认的TrustManager

                manager = chooseTrustManager(trustManagers);

            } else {

//否则使用不安全的TrustManager

                manager = UnSafeTrustManager;

            }

// 创建TLS类型的SSLContext对象， that uses our TrustManager

            SSLContext sslContext = SSLContext.getInstance("TLS");

            // 用上面得到的trustManagers初始化SSLContext，这样sslContext就会信任keyStore中的证书

// 第一个参数是授权的密钥管理器，用来授权验证，比如授权自签名的证书验证。第二个是被授权的证书管理器，用来验证服务器端的证书

            sslContext.init(keyManagers, new TrustManager[]{manager}, null);

            // 通过sslContext获取SSLSocketFactory对象

            sslParams.sSLSocketFactory = sslContext.getSocketFactory();

            sslParams.trustManager = manager;

            return sslParams;

        } catch (NoSuchAlgorithmException e) {

            throw new AssertionError(e);

        } catch (KeyManagementException e) {

            throw new AssertionError(e);

        }

    }

    private static KeyManager[] prepareKeyManager(InputStream bksFile, String password) {

        try {

            if (bksFile == null || password == null) return null;

            KeyStore clientKeyStore = KeyStore.getInstance("BKS");

            clientKeyStore.load(bksFile, password.toCharArray());

            KeyManagerFactory kmf = KeyManagerFactory.getInstance(KeyManagerFactory.getDefaultAlgorithm());

            kmf.init(clientKeyStore, password.toCharArray());

            return kmf.getKeyManagers();

        } catch (Exception e) {

            e.printStackTrace();

        }

        return null;

    }

    private static TrustManager[] prepareTrustManager(InputStream... certificates) {

        if (certificates == null || certificates.length <= 0) return null;

        try {

            CertificateFactory certificateFactory = CertificateFactory.getInstance("X.509");

            // 创建一个默认类型的KeyStore，存储我们信任的证书

            KeyStore keyStore = KeyStore.getInstance(KeyStore.getDefaultType());

            keyStore.load(null);

            int index = 0;

            for (InputStream certStream : certificates) {

                String certificateAlias = Integer.toString(index++);

                // 证书工厂根据证书文件的流生成证书 cert

                Certificate cert = certificateFactory.generateCertificate(certStream);

                // 将 cert 作为可信证书放入到keyStore中

                keyStore.setCertificateEntry(certificateAlias, cert);

                try {

                    if (certStream != null) certStream.close();

                } catch (IOException e) {

                    e.printStackTrace();

                }

            }

//我们创建一个默认类型的TrustManagerFactory

            TrustManagerFactory tmf = TrustManagerFactory.getInstance(TrustManagerFactory.getDefaultAlgorithm());

            //用我们之前的keyStore实例初始化TrustManagerFactory，这样tmf就会信任keyStore中的证书

            tmf.init(keyStore);

            //通过tmf获取TrustManager数组，TrustManager也会信任keyStore中的证书

            return tmf.getTrustManagers();

        } catch (Exception e) {

            e.printStackTrace();

        }

        return null;

    }

    private static X509TrustManager chooseTrustManager(TrustManager[] trustManagers) {

        for (TrustManager trustManager : trustManagers) {

            if (trustManager instanceof X509TrustManager) {

                return (X509TrustManager) trustManager;

            }

        }

        return null;

    }

    /**
     * 为了解决客户端不信任服务器数字证书的问题，网络上大部分的解决方案都是让客户端不对证书做任何检查，
     * <p>
     * 这是一种有很大安全漏洞的办法
     */

    public static X509TrustManager UnSafeTrustManager = new X509TrustManager() {

        @Override

        public void checkClientTrusted(X509Certificate[] chain, String authType) throws CertificateException {

        }

        @Override

        public void checkServerTrusted(X509Certificate[] chain, String authType) throws CertificateException {

        }

        @Override

        public X509Certificate[] getAcceptedIssuers() {

            return new X509Certificate[]{};

        }

    };

    /**
     * 此类是用于主机名验证的基接口。 在握手期间，如果 URL 的主机名和服务器的标识主机名不匹配，
     * <p>
     * 则验证机制可以回调此接口的实现程序来确定是否应该允许此连接。策略可以是基于证书的或依赖于其他验证方案。
     * <p>
     * 当验证 URL 主机名使用的默认规则失败时使用这些回调。如果主机名是可接受的，则返回 true
     */

    public static HostnameVerifier UnSafeHostnameVerifier = new HostnameVerifier() {

        @Override

        public boolean verify(String hostname, SSLSession session) {

            return true;

        }

    };

}
